Move format specifier lexing from syntax to ide_db

crates/ide/src/syntax_highlighting.rs

@@ -16,7 +16,7 @@ use hir::{InFile, Name, Semantics};
 use ide_db::RootDatabase;
 use rustc_hash::FxHashMap;
 use syntax::{
-    ast::{self, HasFormatSpecifier},
+    ast::{self, IsString},
     AstNode, AstToken, NodeOrToken,
     SyntaxKind::*,
     SyntaxNode, TextRange, WalkEvent, T,
@@ -336,17 +336,19 @@ fn traverse(
                 }
                 highlight_format_string(hl, &string, &expanded_string, range);
                 // Highlight escape sequences
-                if let Some(char_ranges) = string.char_ranges() {
-                    for (piece_range, _) in char_ranges.iter().filter(|(_, char)| char.is_ok()) {
-                        if string.text()[piece_range.start().into()..].starts_with('\\') {
-                            hl.add(HlRange {
-                                range: piece_range + range.start(),
-                                highlight: HlTag::EscapeSequence.into(),
-                                binding_hash: None,
-                            });
-                        }
+                string.escaped_char_ranges(&mut |piece_range, char| {
+                    if char.is_err() {
+                        return;
                     }
-                }
+
+                    if string.text()[piece_range.start().into()..].starts_with('\\') {
+                        hl.add(HlRange {
+                            range: piece_range + range.start(),
+                            highlight: HlTag::EscapeSequence.into(),
+                            binding_hash: None,
+                        });
+                    }
+                });
             }
         }
 

crates/ide/src/syntax_highlighting/format.rs

@@ -1,9 +1,9 @@
 //! Syntax highlighting for format macro strings.
-use ide_db::{helpers::format_string::is_format_string, SymbolKind};
-use syntax::{
-    ast::{self, FormatSpecifier, HasFormatSpecifier},
-    TextRange,
+use ide_db::{
+    helpers::format_string::{is_format_string, lex_format_specifiers, FormatSpecifier},
+    SymbolKind,
 };
+use syntax::{ast, TextRange};
 
 use crate::{syntax_highlighting::highlights::Highlights, HlRange, HlTag};
 
@@ -17,7 +17,7 @@ pub(super) fn highlight_format_string(
         return;
     }
 
-    string.lex_format_specifier(|piece_range, kind| {
+    lex_format_specifiers(string, &mut |piece_range, kind| {
         if let Some(highlight) = highlight_format_specifier(kind) {
             stack.add(HlRange {
                 range: piece_range + range.start(),

crates/ide_db/src/helpers/format_string.rs

@@ -1,5 +1,8 @@
 //! Tools to work with format string literals for the `format_args!` family of macros.
-use syntax::{ast, AstNode, AstToken};
+use syntax::{
+    ast::{self, IsString},
+    AstNode, AstToken, TextRange,
+};
 
 pub fn is_format_string(string: &ast::String) -> bool {
     // Check if `string` is a format string argument of a macro invocation.
@@ -10,7 +13,7 @@ pub fn is_format_string(string: &ast::String) -> bool {
     //
     // This setup lets us correctly highlight the components of `concat!("{}", "bla")` format
     // strings. It still fails for `concat!("{", "}")`, but that is rare.
-
+    format!("{string} {bar}", bar = string);
     (|| {
         let macro_call = string.syntax().ancestors().find_map(ast::MacroCall::cast)?;
         let name = macro_call.path()?.segment()?.name_ref()?;
@@ -29,3 +32,261 @@ pub fn is_format_string(string: &ast::String) -> bool {
     })()
     .is_some()
 }
+
+#[derive(Debug)]
+pub enum FormatSpecifier {
+    Open,
+    Close,
+    Integer,
+    Identifier,
+    Colon,
+    Fill,
+    Align,
+    Sign,
+    NumberSign,
+    Zero,
+    DollarSign,
+    Dot,
+    Asterisk,
+    QuestionMark,
+}
+
+pub fn lex_format_specifiers(
+    string: &ast::String,
+    mut callback: &mut dyn FnMut(TextRange, FormatSpecifier),
+) {
+    let mut char_ranges = Vec::new();
+    string.escaped_char_ranges(&mut |range, res| char_ranges.push((range, res)));
+    let mut chars = char_ranges
+        .iter()
+        .filter_map(|(range, res)| Some((*range, *res.as_ref().ok()?)))
+        .peekable();
+
+    while let Some((range, first_char)) = chars.next() {
+        if let '{' = first_char {
+            // Format specifier, see syntax at https://doc.rust-lang.org/std/fmt/index.html#syntax
+            if let Some((_, '{')) = chars.peek() {
+                // Escaped format specifier, `{{`
+                chars.next();
+                continue;
+            }
+
+            callback(range, FormatSpecifier::Open);
+
+            // check for integer/identifier
+            let (_, int_char) = chars.peek().copied().unwrap_or_default();
+            match int_char {
+                // integer
+                '0'..='9' => read_integer(&mut chars, &mut callback),
+                // identifier
+                c if c == '_' || c.is_alphabetic() => read_identifier(&mut chars, &mut callback),
+                _ => {}
+            }
+
+            if let Some((_, ':')) = chars.peek() {
+                skip_char_and_emit(&mut chars, FormatSpecifier::Colon, &mut callback);
+
+                // check for fill/align
+                let mut cloned = chars.clone().take(2);
+                let (_, first) = cloned.next().unwrap_or_default();
+                let (_, second) = cloned.next().unwrap_or_default();
+                match second {
+                    '<' | '^' | '>' => {
+                        // alignment specifier, first char specifies fillment
+                        skip_char_and_emit(&mut chars, FormatSpecifier::Fill, &mut callback);
+                        skip_char_and_emit(&mut chars, FormatSpecifier::Align, &mut callback);
+                    }
+                    _ => {
+                        if let '<' | '^' | '>' = first {
+                            skip_char_and_emit(&mut chars, FormatSpecifier::Align, &mut callback);
+                        }
+                    }
+                }
+
+                // check for sign
+                match chars.peek().copied().unwrap_or_default().1 {
+                    '+' | '-' => {
+                        skip_char_and_emit(&mut chars, FormatSpecifier::Sign, &mut callback);
+                    }
+                    _ => {}
+                }
+
+                // check for `#`
+                if let Some((_, '#')) = chars.peek() {
+                    skip_char_and_emit(&mut chars, FormatSpecifier::NumberSign, &mut callback);
+                }
+
+                // check for `0`
+                let mut cloned = chars.clone().take(2);
+                let first = cloned.next().map(|next| next.1);
+                let second = cloned.next().map(|next| next.1);
+
+                if first == Some('0') && second != Some('$') {
+                    skip_char_and_emit(&mut chars, FormatSpecifier::Zero, &mut callback);
+                }
+
+                // width
+                match chars.peek().copied().unwrap_or_default().1 {
+                    '0'..='9' => {
+                        read_integer(&mut chars, &mut callback);
+                        if let Some((_, '$')) = chars.peek() {
+                            skip_char_and_emit(
+                                &mut chars,
+                                FormatSpecifier::DollarSign,
+                                &mut callback,
+                            );
+                        }
+                    }
+                    c if c == '_' || c.is_alphabetic() => {
+                        read_identifier(&mut chars, &mut callback);
+
+                        if chars.peek().map(|&(_, c)| c) == Some('?') {
+                            skip_char_and_emit(
+                                &mut chars,
+                                FormatSpecifier::QuestionMark,
+                                &mut callback,
+                            );
+                        }
+
+                        // can be either width (indicated by dollar sign, or type in which case
+                        // the next sign has to be `}`)
+                        let next = chars.peek().map(|&(_, c)| c);
+
+                        match next {
+                            Some('$') => skip_char_and_emit(
+                                &mut chars,
+                                FormatSpecifier::DollarSign,
+                                &mut callback,
+                            ),
+                            Some('}') => {
+                                skip_char_and_emit(
+                                    &mut chars,
+                                    FormatSpecifier::Close,
+                                    &mut callback,
+                                );
+                                continue;
+                            }
+                            _ => continue,
+                        };
+                    }
+                    _ => {}
+                }
+
+                // precision
+                if let Some((_, '.')) = chars.peek() {
+                    skip_char_and_emit(&mut chars, FormatSpecifier::Dot, &mut callback);
+
+                    match chars.peek().copied().unwrap_or_default().1 {
+                        '*' => {
+                            skip_char_and_emit(
+                                &mut chars,
+                                FormatSpecifier::Asterisk,
+                                &mut callback,
+                            );
+                        }
+                        '0'..='9' => {
+                            read_integer(&mut chars, &mut callback);
+                            if let Some((_, '$')) = chars.peek() {
+                                skip_char_and_emit(
+                                    &mut chars,
+                                    FormatSpecifier::DollarSign,
+                                    &mut callback,
+                                );
+                            }
+                        }
+                        c if c == '_' || c.is_alphabetic() => {
+                            read_identifier(&mut chars, &mut callback);
+                            if chars.peek().map(|&(_, c)| c) != Some('$') {
+                                continue;
+                            }
+                            skip_char_and_emit(
+                                &mut chars,
+                                FormatSpecifier::DollarSign,
+                                &mut callback,
+                            );
+                        }
+                        _ => {
+                            continue;
+                        }
+                    }
+                }
+
+                // type
+                match chars.peek().copied().unwrap_or_default().1 {
+                    '?' => {
+                        skip_char_and_emit(
+                            &mut chars,
+                            FormatSpecifier::QuestionMark,
+                            &mut callback,
+                        );
+                    }
+                    c if c == '_' || c.is_alphabetic() => {
+                        read_identifier(&mut chars, &mut callback);
+
+                        if chars.peek().map(|&(_, c)| c) == Some('?') {
+                            skip_char_and_emit(
+                                &mut chars,
+                                FormatSpecifier::QuestionMark,
+                                &mut callback,
+                            );
+                        }
+                    }
+                    _ => {}
+                }
+            }
+
+            if let Some((_, '}')) = chars.peek() {
+                skip_char_and_emit(&mut chars, FormatSpecifier::Close, &mut callback);
+            }
+            continue;
+        }
+    }
+
+    fn skip_char_and_emit<I, F>(
+        chars: &mut std::iter::Peekable<I>,
+        emit: FormatSpecifier,
+        callback: &mut F,
+    ) where
+        I: Iterator<Item = (TextRange, char)>,
+        F: FnMut(TextRange, FormatSpecifier),
+    {
+        let (range, _) = chars.next().unwrap();
+        callback(range, emit);
+    }
+
+    fn read_integer<I, F>(chars: &mut std::iter::Peekable<I>, callback: &mut F)
+    where
+        I: Iterator<Item = (TextRange, char)>,
+        F: FnMut(TextRange, FormatSpecifier),
+    {
+        let (mut range, c) = chars.next().unwrap();
+        assert!(c.is_ascii_digit());
+        while let Some(&(r, next_char)) = chars.peek() {
+            if next_char.is_ascii_digit() {
+                chars.next();
+                range = range.cover(r);
+            } else {
+                break;
+            }
+        }
+        callback(range, FormatSpecifier::Integer);
+    }
+
+    fn read_identifier<I, F>(chars: &mut std::iter::Peekable<I>, callback: &mut F)
+    where
+        I: Iterator<Item = (TextRange, char)>,
+        F: FnMut(TextRange, FormatSpecifier),
+    {
+        let (mut range, c) = chars.next().unwrap();
+        assert!(c.is_alphabetic() || c == '_');
+        while let Some(&(r, next_char)) = chars.peek() {
+            if next_char == '_' || next_char.is_ascii_digit() || next_char.is_alphabetic() {
+                chars.next();
+                range = range.cover(r);
+            } else {
+                break;
+            }
+        }
+        callback(range, FormatSpecifier::Identifier);
+    }
+}

crates/syntax/src/ast.rs

@@ -25,10 +25,7 @@ pub use self::{
         SlicePatComponents, StructKind, TypeBoundKind, VisibilityKind,
     },
     operators::{ArithOp, BinaryOp, CmpOp, LogicOp, Ordering, RangeOp, UnaryOp},
-    token_ext::{
-        CommentKind, CommentPlacement, CommentShape, FormatSpecifier, HasFormatSpecifier, IsString,
-        QuoteOffsets, Radix,
-    },
+    token_ext::{CommentKind, CommentPlacement, CommentShape, IsString, QuoteOffsets, Radix},
     traits::{
         DocCommentIter, HasArgList, HasAttrs, HasDocComments, HasGenericParams, HasLoopBody,
         HasModuleItem, HasName, HasTypeBounds, HasVisibility,

crates/syntax/src/ast/token_ext.rs

@@ -164,6 +164,25 @@ pub trait IsString: AstToken {
     fn close_quote_text_range(&self) -> Option<TextRange> {
         self.quote_offsets().map(|it| it.quotes.1)
     }
+    fn escaped_char_ranges(
+        &self,
+        cb: &mut dyn FnMut(TextRange, Result<char, rustc_lexer::unescape::EscapeError>),
+    ) {
+        let text_range_no_quotes = match self.text_range_between_quotes() {
+            Some(it) => it,
+            None => return,
+        };
+
+        let start = self.syntax().text_range().start();
+        let text = &self.text()[text_range_no_quotes - start];
+        let offset = text_range_no_quotes.start() - start;
+
+        unescape_literal(text, Mode::Str, &mut |range, unescaped_char| {
+            let text_range =
+                TextRange::new(range.start.try_into().unwrap(), range.end.try_into().unwrap());
+            cb(text_range + offset, unescaped_char);
+        });
+    }
 }
 
 impl IsString for ast::String {}
@@ -257,299 +276,6 @@ impl ast::ByteString {
     }
 }
 
-#[derive(Debug)]
-pub enum FormatSpecifier {
-    Open,
-    Close,
-    Integer,
-    Identifier,
-    Colon,
-    Fill,
-    Align,
-    Sign,
-    NumberSign,
-    Zero,
-    DollarSign,
-    Dot,
-    Asterisk,
-    QuestionMark,
-}
-
-pub trait HasFormatSpecifier: AstToken {
-    fn char_ranges(
-        &self,
-    ) -> Option<Vec<(TextRange, Result<char, rustc_lexer::unescape::EscapeError>)>>;
-
-    fn lex_format_specifier<F>(&self, mut callback: F)
-    where
-        F: FnMut(TextRange, FormatSpecifier),
-    {
-        let char_ranges = match self.char_ranges() {
-            Some(char_ranges) => char_ranges,
-            None => return,
-        };
-        let mut chars = char_ranges
-            .iter()
-            .filter_map(|(range, res)| Some((*range, *res.as_ref().ok()?)))
-            .peekable();
-
-        while let Some((range, first_char)) = chars.next() {
-            if let '{' = first_char {
-                // Format specifier, see syntax at https://doc.rust-lang.org/std/fmt/index.html#syntax
-                if let Some((_, '{')) = chars.peek() {
-                    // Escaped format specifier, `{{`
-                    chars.next();
-                    continue;
-                }
-
-                callback(range, FormatSpecifier::Open);
-
-                // check for integer/identifier
-                let (_, int_char) = chars.peek().copied().unwrap_or_default();
-                match int_char {
-                    // integer
-                    '0'..='9' => read_integer(&mut chars, &mut callback),
-                    // identifier
-                    c if c == '_' || c.is_alphabetic() => {
-                        read_identifier(&mut chars, &mut callback)
-                    }
-                    _ => {}
-                }
-
-                if let Some((_, ':')) = chars.peek() {
-                    skip_char_and_emit(&mut chars, FormatSpecifier::Colon, &mut callback);
-
-                    // check for fill/align
-                    let mut cloned = chars.clone().take(2);
-                    let (_, first) = cloned.next().unwrap_or_default();
-                    let (_, second) = cloned.next().unwrap_or_default();
-                    match second {
-                        '<' | '^' | '>' => {
-                            // alignment specifier, first char specifies fillment
-                            skip_char_and_emit(&mut chars, FormatSpecifier::Fill, &mut callback);
-                            skip_char_and_emit(&mut chars, FormatSpecifier::Align, &mut callback);
-                        }
-                        _ => {
-                            if let '<' | '^' | '>' = first {
-                                skip_char_and_emit(
-                                    &mut chars,
-                                    FormatSpecifier::Align,
-                                    &mut callback,
-                                );
-                            }
-                        }
-                    }
-
-                    // check for sign
-                    match chars.peek().copied().unwrap_or_default().1 {
-                        '+' | '-' => {
-                            skip_char_and_emit(&mut chars, FormatSpecifier::Sign, &mut callback);
-                        }
-                        _ => {}
-                    }
-
-                    // check for `#`
-                    if let Some((_, '#')) = chars.peek() {
-                        skip_char_and_emit(&mut chars, FormatSpecifier::NumberSign, &mut callback);
-                    }
-
-                    // check for `0`
-                    let mut cloned = chars.clone().take(2);
-                    let first = cloned.next().map(|next| next.1);
-                    let second = cloned.next().map(|next| next.1);
-
-                    if first == Some('0') && second != Some('$') {
-                        skip_char_and_emit(&mut chars, FormatSpecifier::Zero, &mut callback);
-                    }
-
-                    // width
-                    match chars.peek().copied().unwrap_or_default().1 {
-                        '0'..='9' => {
-                            read_integer(&mut chars, &mut callback);
-                            if let Some((_, '$')) = chars.peek() {
-                                skip_char_and_emit(
-                                    &mut chars,
-                                    FormatSpecifier::DollarSign,
-                                    &mut callback,
-                                );
-                            }
-                        }
-                        c if c == '_' || c.is_alphabetic() => {
-                            read_identifier(&mut chars, &mut callback);
-
-                            if chars.peek().map(|&(_, c)| c) == Some('?') {
-                                skip_char_and_emit(
-                                    &mut chars,
-                                    FormatSpecifier::QuestionMark,
-                                    &mut callback,
-                                );
-                            }
-
-                            // can be either width (indicated by dollar sign, or type in which case
-                            // the next sign has to be `}`)
-                            let next = chars.peek().map(|&(_, c)| c);
-
-                            match next {
-                                Some('$') => skip_char_and_emit(
-                                    &mut chars,
-                                    FormatSpecifier::DollarSign,
-                                    &mut callback,
-                                ),
-                                Some('}') => {
-                                    skip_char_and_emit(
-                                        &mut chars,
-                                        FormatSpecifier::Close,
-                                        &mut callback,
-                                    );
-                                    continue;
-                                }
-                                _ => continue,
-                            };
-                        }
-                        _ => {}
-                    }
-
-                    // precision
-                    if let Some((_, '.')) = chars.peek() {
-                        skip_char_and_emit(&mut chars, FormatSpecifier::Dot, &mut callback);
-
-                        match chars.peek().copied().unwrap_or_default().1 {
-                            '*' => {
-                                skip_char_and_emit(
-                                    &mut chars,
-                                    FormatSpecifier::Asterisk,
-                                    &mut callback,
-                                );
-                            }
-                            '0'..='9' => {
-                                read_integer(&mut chars, &mut callback);
-                                if let Some((_, '$')) = chars.peek() {
-                                    skip_char_and_emit(
-                                        &mut chars,
-                                        FormatSpecifier::DollarSign,
-                                        &mut callback,
-                                    );
-                                }
-                            }
-                            c if c == '_' || c.is_alphabetic() => {
-                                read_identifier(&mut chars, &mut callback);
-                                if chars.peek().map(|&(_, c)| c) != Some('$') {
-                                    continue;
-                                }
-                                skip_char_and_emit(
-                                    &mut chars,
-                                    FormatSpecifier::DollarSign,
-                                    &mut callback,
-                                );
-                            }
-                            _ => {
-                                continue;
-                            }
-                        }
-                    }
-
-                    // type
-                    match chars.peek().copied().unwrap_or_default().1 {
-                        '?' => {
-                            skip_char_and_emit(
-                                &mut chars,
-                                FormatSpecifier::QuestionMark,
-                                &mut callback,
-                            );
-                        }
-                        c if c == '_' || c.is_alphabetic() => {
-                            read_identifier(&mut chars, &mut callback);
-
-                            if chars.peek().map(|&(_, c)| c) == Some('?') {
-                                skip_char_and_emit(
-                                    &mut chars,
-                                    FormatSpecifier::QuestionMark,
-                                    &mut callback,
-                                );
-                            }
-                        }
-                        _ => {}
-                    }
-                }
-
-                if let Some((_, '}')) = chars.peek() {
-                    skip_char_and_emit(&mut chars, FormatSpecifier::Close, &mut callback);
-                }
-                continue;
-            }
-        }
-
-        fn skip_char_and_emit<I, F>(
-            chars: &mut std::iter::Peekable<I>,
-            emit: FormatSpecifier,
-            callback: &mut F,
-        ) where
-            I: Iterator<Item = (TextRange, char)>,
-            F: FnMut(TextRange, FormatSpecifier),
-        {
-            let (range, _) = chars.next().unwrap();
-            callback(range, emit);
-        }
-
-        fn read_integer<I, F>(chars: &mut std::iter::Peekable<I>, callback: &mut F)
-        where
-            I: Iterator<Item = (TextRange, char)>,
-            F: FnMut(TextRange, FormatSpecifier),
-        {
-            let (mut range, c) = chars.next().unwrap();
-            assert!(c.is_ascii_digit());
-            while let Some(&(r, next_char)) = chars.peek() {
-                if next_char.is_ascii_digit() {
-                    chars.next();
-                    range = range.cover(r);
-                } else {
-                    break;
-                }
-            }
-            callback(range, FormatSpecifier::Integer);
-        }
-
-        fn read_identifier<I, F>(chars: &mut std::iter::Peekable<I>, callback: &mut F)
-        where
-            I: Iterator<Item = (TextRange, char)>,
-            F: FnMut(TextRange, FormatSpecifier),
-        {
-            let (mut range, c) = chars.next().unwrap();
-            assert!(c.is_alphabetic() || c == '_');
-            while let Some(&(r, next_char)) = chars.peek() {
-                if next_char == '_' || next_char.is_ascii_digit() || next_char.is_alphabetic() {
-                    chars.next();
-                    range = range.cover(r);
-                } else {
-                    break;
-                }
-            }
-            callback(range, FormatSpecifier::Identifier);
-        }
-    }
-}
-
-impl HasFormatSpecifier for ast::String {
-    fn char_ranges(
-        &self,
-    ) -> Option<Vec<(TextRange, Result<char, rustc_lexer::unescape::EscapeError>)>> {
-        let text = self.text();
-        let text = &text[self.text_range_between_quotes()? - self.syntax().text_range().start()];
-        let offset = self.text_range_between_quotes()?.start() - self.syntax().text_range().start();
-
-        let mut res = Vec::with_capacity(text.len());
-        unescape_literal(text, Mode::Str, &mut |range, unescaped_char| {
-            res.push((
-                TextRange::new(range.start.try_into().unwrap(), range.end.try_into().unwrap())
-                    + offset,
-                unescaped_char,
-            ));
-        });
-
-        Some(res)
-    }
-}
-
 impl ast::IntNumber {
     pub fn radix(&self) -> Radix {
         match self.text().get(..2).unwrap_or_default() {